ACCEPTABILITY OF INTERFERON-GAMMA RELEASE ASSAYS FOR USE IN - - PowerPoint PPT Presentation

ACCEPTABILITY OF INTERFERON-GAMMA RELEASE ASSAYS FOR USE IN ROUTINE EMPLOYEE TB TESTING

Yael Hirsch-Moverman, MPH Julie Franks, PhD February 10, 2011

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Background

• CDC guidelines recommend TB testing for

healthcare workers (HCWs) upon hire and periodically thereafter using either

• Tuberculin skin test (TST)
• Interferon-gamma release assays (IGRAs), such

as QFT-G and T-SPOT

• IGRAs are relatively new diagnostic tests for

TB infection

• Little known about their acceptability among

healthcare providers and patients, specifically HCWs

Task Order 18 Objectives

• To evaluate performance characteristics of QFT

and T-SPOT compared with TST for detecting LTBI in HCWs undergoing routine screening

–Test result stability over time (i.e. conversion, reversion) –Reproducibility –Test, re-test repeatability –Estimated sensitivity and specificity –% of failed tests –Impact of TST on IGRA results

• To determine costs, cost-effectiveness
• To determine and compare acceptability of tests

among participants

Design and Population

• Longitudinal study
• HCWs undergoing routine LTBI testing
• 4 sites: Denver, Houston, Baltimore, NYC
• Inclusion:

– ≥18 yrs; informed consent; undergoing routine screening

• Exclusion:

– Current or prior active TB; TST within 6 months prior to enrollment

• Target sample size ∼ 2500
• 2,493 completed baseline assessment

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Acceptability Objectives

• To assess knowledge, attitudes, beliefs,

practices, and barriers in the use of IGRAs with respect to: – acceptability and usability of testing procedures – patient-provider communication about IGRAs – barriers and facilitators in the use of the IGRAs

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Acceptability Components

• Quantitative - collection of quantitative

data assessing individual responses of HCWs to research questions

• Qualitative - formative research utilizing:

– focus groups with HCWs – key informant interviews with providers

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Quantitative Component

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Study Population and Methods

• The first 100 participants enrolled at each

site asked to respond to an acceptability questionnaire

• Assessment tool consisted of 13 questions

designed to elicit attitudes regarding:

– the use of TSTs and IGRAs – confidence in the results of each test – likelihood of taking LTBI treatment based on the results of either test

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Demographics

Acceptability N = 407 Median age (range) 37 (20-73) Gender (female) 81.8% Race/Ethnicity Hispanic 24.3% African-American 15.7% Caucasian 52.1% Asian 5.7% Other 2.2% Foreign-born 17.4% BCG vaccinated 11.8% HIV-infected 0.2%

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Work Environment

N = 407 How frequent in-person contact with pts?

• never

16.9%

• rare (<5%)

11.9%

• occasional (5-20%)

10.6%

• moderate (21-50%)

7.1%

• frequent (>50%)

53.4% Job location past year:

• not used for pt care

18.2%

• rare or no TB pts

28.0%

• occasional reports of TB pts

31.2%

• frequent reports of TB pts

11.8%

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Awareness of Blood Tests

How much heard of blood tests? N=407 Have not heard 75.2% Heard a little 18.9% Heard a lot 5.4% Don’t know 0.3% Prefer not to answer 0.3%

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Testing Scenarios

If… TST+, believe result Yes 69.0% No 22.4% DK 8.4%

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Testing Scenarios

If… TST+, believe result TST+, willing to take TLTBI Yes 69.0% 79.4% No 22.4% 8.1% DK 8.4% 12.5%

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Testing Scenarios

If… TST+, believe result TST+, willing to take TLTBI Blood test +, believe result Yes 69.0% 79.4% 75.7% No 22.4% 8.1% 7.1% DK 8.4% 12.5% 17.2%

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Testing Scenarios

If… TST+, believe result TST+, willing to take TLTBI Blood test +, believe result Blood test +, willing to take TLTBI Yes 69.0% 79.4% 75.7% 78.9% No 22.4% 8.1% 7.1% 6.1% DK 8.4% 12.5% 17.2% 14.7%

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General Testing Preferences

Factor/Importance No Low Neutral Moderate High Side effects from test 5.9 9.1 11.8 30.5 42.3 Accuracy of results 1.0 0.5 3.4 10.3 84.0 Amount of time test in use 5.4 9.1 27.0 32.9 25.3 Effect on ability to work 4.4 3.7 9.8 26.3 55.0 Ability to understand how test works 3.4 5.7 13.3 27.3 50.1 Pain of test 11.1 14.0 26.0 24.3 24.1 Convenience of test 4.4 7.4 22.9 33.9 31.2 Ability to understand what results mean 1.5 1.5 4.9 21.4 70.3 Which test HCP recommends 5.4 3.7 13.0 31.0 46.4 How much test costs to you 7.1 6.1 20.4 27.8 38.1

General Testing Preferences

Factor/Importance No Low Neutral Moderate High Side effects from test 5.9 9.1 11.8 30.5 42.3 Accuracy of results 1.0 0.5 3.4 10.3 84.0 Amount of time test in use 5.4 9.1 27.0 32.9 25.3 Effect on ability to work 4.4 3.7 9.8 26.3 55.0 Ability to understand how test works 3.4 5.7 13.3 27.3 50.1 Pain of test 11.1 14.0 26.0 24.3 24.1 Convenience of test 4.4 7.4 22.9 33.9 31.2 Ability to understand what results mean 1.5 1.5 4.9 21.4 70.3 Which test HCP recommends 5.4 3.7 13.0 31.0 46.4 How much test costs to you 7.1 6.1 20.4 27.8 38.1

Most important factor: accuracy of results

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BCG Vaccination

BCG vaccination N=407 Yes 10.8% No 81.8% DK 7.1% PNTA 0.3% BCG vaccinated N=44 Not BCG vaccinated N=363 Importance of test ability to tell if infected

• No importance

0% 0%

• Low importance

2.3% 0.6%

• Neutral

2.3% 1.4%

• Moderate importance

4.6% 11.0%

• High importance

88.6% 85.1%

• DK

2.3% 0.6%

• PNTA

0.0% 1.4%

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Test Preference

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Test Preference

21.4% 50.1% 23.3% 4.9% 0.3%

Test Preference - Reason

Reason prefer TST N=85 Familiarity with test 28.2% Convenience 24.7% Less invasive/painful 23.5% Blood draw is hard 3.5% Can see results 7.1% Other 10.6% Accuracy 2.4%

Test Preference - Reason

Reason prefer TST N=85 Familiarity with test 28.2% Less invasive/painful 23.5% Convenience 24.7% Blood draw is hard 3.5% Can see results 7.1% Other 10.6% Accuracy 2.4% Reason prefer blood test N=202 Convenience 48.0% Accuracy 34.2% Convenient/accurate 11.4% Other 4.0% Not injected with antigen 2.5%

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Fears of Tests

Fear of… injection of fluid N=407 blood test N=407 Yes 10.1% 10.1% No 88.7% 88.7% DK 1.0% 1.0% PNTA 0.3% 0.3%

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Belief in Tests

If TST+ and blood test is negative N=407 TST 14.5% Blood test 53.6% DK 31.5% PTNA 0.5%

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Belief in Tests

If TST+ and blood test is negative N=407 TST 14.5% Blood test 53.6% DK 31.5% PTNA 0.5% If TST- and blood test is positive N=407 TST 9.8% Blood test 54.6% DK 35.1% PTNA 0.5%

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Conclusions

• Although HCWs indicated preference for

IGRAs over the TST and further expressed confidence in IGRA results compared to TST results, the likelihood that HCWs would initiate LTBI treatment based on positive results from either test remained the same.

• Further studies are needed to determine if

IGRA positive results will have any impact on HCWs actual acceptance and completion of LTBI treatment.

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Qualitative Component Focus Groups

Key Informant Interviews

Rationale for Qualitative Sub-study

• Provide contextual and anecdotal data to

enrich quantitative acceptability data

• Explore factors influencing implementation of

LTBI testing and treatment guidelines in

• ccupational health settings

– HCWs’ knowledge, attitudes, and practices – provider approaches to implementation – institutional factors

• Identify areas for further investigation into

LTBI testing and treatment in occupational health settings

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Background

• Joseph et al (2004) conducted focus groups in

4 healthcare settings exploring HCWs’ reasons for adherence/nonadherence to

• ccupational health requirements for LTBI

testing and treatment

• Knowledge and attitudes about LTBI and

treatment of LTBI influenced HCW adherence to recommendations

• Institutional factors also influential

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Methods

• Purposive sampling of HCWs and providers

experienced in transition from TST to IGRA in serial screening

– purposive sample is a non-representative sample of a specific sub-population defined by research question

• Semi-structured interview guides refined after

initial round of focus groups with providers

• HCWs recruited through occupational health

staff for participation in focus groups

• Providers recruited directly for individual

interviews

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Methods (con’t)

• 5 focus groups at 3 sites with total of 46

HCWs (7/08-9/09)

• 7 key informant interviews at 2 sites (9/09-

4/10)

• Audio-recorded interviews transcribed and

entered in Atlas.ti database for analysis

• Coding categories determined a priori and as

emerged from transcripts

• Analysis on-going

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HCWs Experiences with TB Testing

Factors Influencing Preference for Testing Method

Factor IGRA TST Convenience of administration single visit two visits Perceived drawbacks reluctance to get blood drawn misgivings about tuberculin injection Confidence in method perceived inherent accuracy

• f blood test

lack of experience w/IGRAs qualitative presentation of results administrator variability subjectivity of interpretation influence of BCG familiarity w/test Cost/Logistics general unease about cost

• f IGRA

ease of use in the field

HCWs Experiences with TB Testing

• Factors influencing acceptability are complex

– accuracy, convenience, implications of cost

• Perceived consequences of testing

– repercussions of inaccurate diagnosis in work settings – confusion about LTBI and rationale for its treatment (“why don’t they just x-ray everyone?”) – misgivings about need for and toxicity of LTBI treatment

• Need for information about testing rationale

and methods

– in retrospect, desire for more information about testing – rationale for new procedures in work setting – information is more valuable when provided in the health care encounter

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General HCW Themes

• HCWs identified conveniences and drawbacks

in both TST and IGRAs

• See IGRAs as potential improvement but

misgivings persist:

– Perceived lack of information about IGRAs – Interpretation of test not understood – Unease concerning cost of IGRA

• Low awareness of rationale for routine

screening in HCWs and treatment of LTBI

• Range of preferences for education

– Desire for information that addresses HCWs as patients

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Provider Themes

• Implementation of IGRAs requires increased

coordination with other departments and

• utside entities

– “QFT is a clinic within the clinic” – Blood draw implies more intensive patient [HCW] interaction

• Shift from provider-based to laboratory

assessment

– perceived as beneficial BUT – implies loss of provider control over process: “a doctor looking at a patient’s arm at least sort of knows what to say to a patient, whereas when they get lab results, sometimes if they’re not really sure what the lab results mean.”

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Provider Themes

• Challenges of interpreting QFT results

– difficulty of interpreting indeterminate results – May be reduced by reliance on actual results, not categorization as negative or positive – patient history and consultation with colleagues remain essential to diagnostic process

• Limited role of IGRAs in treatment for LTBI

– diagnostic tools are only part of complex interaction between patient and provider – distinction between uptake of LTBI treatment (facilitated by use of IGRA) and adherence to treatment (multifactorial)

• Benefit of sharing information about use of

IGRAs in routine occupational health settings

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Preliminary Qualitative Conclusions

• Appreciation of potential of IGRAs to detect

TB infection

• HWCs’ concerns about the overall rationale

for LTBI testing and treatment

• Perceived need for more information about

performance of IGRAs

• Provider decision to recommend treatment

based on complex set of factors, of which testing method is a part

Acknowledgements

TO 18 PIs: Chuck Daley, Susan Dorman, Denise Garrett TO 18 Sites Baltimore: Wendy Cronin, Susan Dorman, Bee Munk Denver: Randall Reves, Kirsten Wall, Bob Belknap NYC: Neil Shluger, Yael Hirsch-Moverman, Joyce Thomas, Julie Franks Texas: Ed Graviss, Larry Teeter CDC Nick DeLuca, Amera Khan, Allison Maiuri, Paul Weinfurter (Westat) Occupational Health Collaborators Jackie Kinnard, Sierra Health, Nevada Susanne Paulson, Nevada Department of Health Jennifer Bunger-Wheeler, Penrose Hospital, Colorado

Thank you!

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